Reinforced thermoplastic patient restraints for radiation therapy

ABSTRACT

A patient restraint member is provided for medical procedures, such as radiation therapy. The restraint member is formed from a sheet of thermoplastic material that can be softened upon heating so as to be formable into a shape corresponding to a patient&#39;s body part to be restricted and setting upon cooling to retain the shape. The sheet includes spaced apart groups of perforations which minimize shrinkage during the formation process. The sheet also includes solid bands extending between the groups of perforation to provide rigidity and strength to the formed sheet.

BACKGROUND OF THE INVENTION

Thermoplastic sheets are well known for use in the field of radiationtherapy treatment, including Intensity Modulated Radiation Therapy(IMRT). Typically, such thermoplastic sheets are heated and then formedto a shape corresponding to the body part to be restrained, such as amask for restraining a patient's head. The sheet is mounted on a framewhich can be secured to a treatment table to facilitate properpositioning of the patient on the table for radiation treatment.

The prior art thermoplastic sheets are solid sheets or perforatedsheets. Solid thermoplastic sheets require much higher forces to form,retain much more heat and tend to have excess shrinkage when formed tothe body shape, all of which leads to patient discomfort. Theperforations serve to reduce the force necessary to form, minimize theheat transferred to the patient, and minimize shrinkage of thethermoplastic material. When the sheet is formed into a facemask, theholes permit a patient to see and breathe through the sheet, and therebyminimize or eliminate claustrophobic feelings. The holes can be punchedinto the sheet, or formed when the sheet is made in an injection moldingprocess. However, totally perforated sheets do not offer the necessaryrigidity which is present in a solid or non-perforated sheet.

Accordingly, a primary objective of the present invention is theprovision of an improved thermoplastic sheet for use in medicalprocedures, including IMRT.

Another objective of the present invention is the provision of animproved thermoplastic sheet having perforations and non-perforatedreinforcing bands.

Further objective of the present invention is the provision of animproved perforated thermoplastic sheet with enhanced rigidity.

Another objective of the present invention is the provision of animproved thermoplastic sheet which is sufficiently rigid, and whichavoids excess shrinkage.

A further objective of the present invention is the provision of animproved thermoplastic sheet, which is comfortable when used on apatient for medical procedures.

These and other objectives will become apparent from the followinginvention.

BRIEF SUMMARY OF THE INVENTION

The improved thermoplastic sheet of the present invention is intendedfor use as a patient restraint member in medical procedures such asradiation therapy treatment, including IMRT. The sheet may take variousforms and shapes to restrain various body parts, including the head,neck, breasts, and hips/pelvic area. The sheet includes a plurality ofgroups of perforations to increase patient comfort with non-perforatedbands extending between the groups of perforation to provide enhancedrigidity. The perforations also minimize shrinkage of the sheet when itis heated, formed, and cooled into a set shape corresponding to the bodypart to be restrained. The perimeter edge of the sheet is free fromperforations. The solid bands extend inwardly from the perimeter edge ofthe sheet The bands may extend completely or partially across the sheetThe solid bands are placed in strategic areas to provide increasedrigidity while the perforations minimize shrinkage. The perforations maybe punched or formed during injection molding.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a thermoplastic sheet formed into amask for restraining a patient's head and mounted onto a radiationtreatment table.

FIGS. 2–5 are each a top plan view of a sheet adapted to be formed intoa head restraint, and showing various alternative embodiments of theperforation groupings and solid reinforcing bands, according to thepresent invention.

FIG. 6 is a top plan view of a thermoplastic sheet adapted to be formedinto a head and shoulder restraint with the perforations and reinforcingbands of the present invention.

FIG. 7 is a top plan of a thermoplastic sheet adapted to be formed intoa breast restraint with the perforations and reinforcing band of thepresent invention.

FIG. 8 is a top plan view of a thermoplastic sheet adapted to be formedinto a hip/pelvic restraint and having the perforations and reinforcingbands of the present invention.

FIG. 9 is a top plan view of a portion of the thermoplastic sheet andassociated U-shaped frame that is shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 a patient 10 as shown on a treatment table 12 in preparationfor radiation therapy on his/her head. The patient's head is restrainedby a thermoplastic mask 14, which has been formed to fit the patient'shead. The mask 14 is mounted on a frame 16, which is adapted to besecured to the treatment table 12 in any convenient manner. For example,the table 12 may include a plurality of indexing notches adapted toreceive an indexing member 18 extending from the frame 16, as describedin the U.S. Pat. No. 6,161,237.

The mask 14 is formed from one of the thermoplastic sheets 20A–20D shownin FIGS. 2–5, respectively. Each sheet 20 includes spaced apart groupsof perforations or holes 22 extending through, or partially through, thesheets 20A–20D. The spacing between the groups of the holes define solidbands 24 which increase the rigidity of the sheets 20A–20D, and thus themask 14. The holes 22 minimize shrinkage of the sheets during the maskformation process. Each of the sheets 20A–D has a non-perforatedperimeter edge 26 for seducement of the sheet to the U-shaped frame 16(FIGS. 1 and 9). Alternatively, the groups of holes 22 may extend to theedge of the sheet 20A–D, which facilitates bonding of the sheet 20A–D tothe frame 16, for example using adhesives or heat. The non-perforatedbands 24 extend inwardly from the perimeter edge 26 of the sheets 20A–D.Some bands 24 may extend completely across the sheets 20 A–D while otherbands 24 extend partially across the sheets. Also, the bands 24 mayextend perpendicularly to the opposite side edges, top edge, or bottomedge, or angularly thereto in a non-perpendicular orientation. As seenin FIG. 5, some of the bands may criss-cross the sheet 20D. The holes 22may be formed by punching or during an injection process used to makethe sheets 20A–D.

FIG. 6 shows another sheet 28 adapted to be formed for restraining thehead and shoulders of a patient. The holes 22 in the sheet 28 minimizeshrinkage, while the solid bands 24 provide increased rigidity for thesheet 28 after it is heated, formed, and cooled to the set shape.

FIG. 7 shows another embodiment of the present invention where in asheet 30 having holes 22 and a solid band 24 is adapted for formationand use in restraining the upper torso of a patient, for example, inbreast radiation treatment. Similarly, FIG. 8 shows a thermoplasticsheet 32 with holes 22 and solid bands 24 according to the presentinvention. The sheet 32 is adapted to be formed and used as a hip/pelvicrestraint. The enlarged holes 34 along the edges of the sheets 30 and 32are used for attaching the sheets 30, 32 to a frame (not shown) which isthen mounted to the treatment table.

Whereas the invention has been shown and described in connection withthe preferred embodiment thereof, it will be understood that anymodifications, substitutions, and additions may be made which are withinthe intended broad scope of the following claims. From the foregoing, itcan be seen that the present invention accomplishes at least all of thestated objectives.

1. A patient restraint member for use in medical procedures, comprising:an integral, unitary sheet having an inner surface and an outer surface,with only a single layer of material between those surfaces, saidmaterial being formed of a thermoplastic material that can be softenedupon heating so as to be formable into a shape corresponding to apatient's body part to be restrained and setting upon cooling to retainthe shape, the sheet having a perimeter edge lying in a common plane andwith the inner surface of the sheet arranged to directly engage thepatient's body part to restrain movement of the patient's body part;spaced apart groups of perforations in the sheet; non-perforated solidbands extending between the groups of perforations; a generally planarU-shaped frame arranged to be attached to and extending around a portionof the perimeter edge of the sheet and being coplanar with the perimeteredge.
 2. The patient restraint member of claim 1 wherein the bandsextend inwardly from the perimeter edge.
 3. The patient restraint memberof claim 2 wherein the bands intersect at a location spaced inwardlyfrom the perimeter edge.
 4. The patient restraint member of claim 2wherein the bands extend perpendicular to the perimeter edge.
 5. Thepatient restraint member of claim 2 wherein the bands extend in anon-perpendicular angle from the perimeter edge.
 6. The patientrestraint member of claim 2 wherein the bands extend completely acrossthe sheet.
 7. The patient restraint member of claim 1 wherein theperimeter edge is without perforations.
 8. The patient restraint memberof claim 1 wherein the bands extend across the sheet.
 9. The patientrestraint member of claim 1 wherein the spaces between the groups ofperforations define the bands.
 10. A patient restraint member for use inmedical procedures, comprising: a partially perforated, integral,unitary sheet having an inner surface and an outer surface, with only asingle layer of material between those surfaces, said material beingformed of a thermoplastic material that can be softened upon heating soas to be formable into a shape corresponding to a patient's body part tobe restrained and setting upon cooling to retain the shape, the sheethaving a perimeter edge lying in a common plane and with the innersurface of the sheet arranged to directly engage the patient's body partto restrain movement of the patient's body part; at least onenon-perforated band extending at least partially across the sheet toenhance rigidity of the sheet; and a generally planar U-shaped framearranged to be attached to and extending around a portion of theperimeter edge of the sheet and being coplanar with the perimeter edge.11. The patient restraint member of claim 10 wherein the at least oneband extends perpendicular to the perimeter edge.
 12. The patientrestraint member of claim 10 the at least one band extends at anon-perpendicular angle to the perimeter edge.
 13. The patient restraintmember of claim 10 wherein the sheet has opposite side edges andopposite top and bottom edges, and wherein the edges are non-perforated.14. The patient restraint member of claim 13 wherein the at least oneband extends between the opposite side edges.
 15. The patient restraintmember of claim 10 wherein the at least one band extends completelyacross the sheet.
 16. The patient restraint member of claim 10 furthercomprising a plurality of non-perforated bands extending inwardly fromthe perimeter edge.
 17. The patient restraint member of claim 10 whereinthe at least one band comprises plural bands which criss-cross thesheet.